diff --git a/ChangeLog b/ChangeLog
index c27dc1155b..cbafd3e280 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Aug 16 15:25:26 2009  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* lib/csv.rb: Change magic comment to US-ASCII in order to
+	  make literals as US-ASCII.
+
 Sun Aug 16 10:45:10 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* regparse.c (parse_char_class, parse_exp, parse_branch),
diff --git a/lib/csv.rb b/lib/csv.rb
index 862839a0e4..aae94888cd 100644
--- a/lib/csv.rb
+++ b/lib/csv.rb
@@ -1,4 +1,4 @@
-# encoding: UTF-8
+# encoding: US-ASCII
 # = csv.rb -- CSV Reading and Writing
 #
 #  Created by James Edward Gray II on 2005-10-31.